Infrared (IR) and ultraviolet (UV) are both forms of electromagnetic radiation, but they have different wavelengths and properties.
Wavelength: The main difference between IR and UV radiation lies in their wavelengths. Infrared radiation has longer wavelengths than visible light, ranging from about 700 nanometers (nm) to 1 millimeter (mm). On the other hand, ultraviolet radiation has shorter wavelengths than visible light, ranging from about 10 nm to 400 nm.
Human Perception: Our eyes are sensitive to a narrow range of wavelengths known as the visible spectrum, which includes colors ranging from red (longer wavelengths) to violet (shorter wavelengths). Since infrared light has longer wavelengths than red light, it falls outside the range of wavelengths that our eyes can detect. Therefore, we cannot see objects that emit only infrared light.
Interaction with Matter: IR and UV radiation interact with matter differently. Infrared radiation is primarily associated with heat and is emitted by objects due to their temperature. It is absorbed by various materials, including living tissue, which is why we often feel the warmth of infrared radiation. Some animals, like snakes, can detect infrared light and use it for hunting.
Ultraviolet radiation, on the other hand, is more energetic than visible light and can cause chemical reactions in certain materials and living organisms. It is responsible for sunburns and can damage our skin and eyes with prolonged exposure. However, our eyes are not sensitive to UV radiation either, as it falls outside the visible spectrum.
While we cannot see infrared light directly, we can use specialized devices such as infrared cameras or sensors to detect and convert infrared radiation into visible images or data. These devices capture the heat signatures emitted by objects and represent them as images that we can perceive.